A two-piece solid golf ball developed to improve the durability of thread wound golf balls, that is, a solid golf ball produced by covering an integrally molded solid core with a cover having excellent cutting resistance (for example, a cover made mainly of an ionomer resin produced by combining metallic ions to ethylene copolymers), has been found to possess an unsatisfactory rebound characteristic. The rebound characteristic largely affects the initial velocity of the ball and is an important property for governing the flight distance of the ball. Accordingly its improvement is necessary.
For a further improvement in the rebound characteristic of the two-piece solid golf ball, methods of improving the rebound characteristic of the solid core or increasing the moment of inertia of the ball, and the like have been considered. Since, however, the rebound characteristic of the solid core is substantially determined by the co-crosslinking, it is very difficult to improve the rebound characteristic. Also, in order to increase the moment of inertia of the ball, trials are being made to change the hardness distribution and weight distribution in the inside of the ball, but satisfactory results have not been obtained because defects, such as a reduction in durability, tend to appear.